The United States joined a controversial proposal by Saudi Arabia and Russia this weekend to weaken a reference to a key report on the severity of global warming, sharpening battle lines at the global climate summit in Poland aimed at gaining consensus over how to combat rising temperatures.

Arguments erupted Saturday night before a United Nations working group focused on science and technology, where the United States teamed with Russia, Saudi Arabia and Kuwait to challenge language that would have welcomed the findings of the landmark report, which said that the world has barely 10 years to cut carbon emissions by nearly half to avoid catastrophic warming.